Angular position measurement using rotary encoder and NI USB 6001

[aksh1552]

Hello, I am trying to calculate angular position (in degrees) using E6B2-CWZ3E rotary incremental encoder and a NI USB 6001 DAQ. Can anyone guide me how to do it?

[ZYOng]

Unfortunately, USB-6001 only supports event counting with its counter.

From USB-6001 Specifications

You would need a better DAQ like USB-621x. See page 112 of USB-621x User Manual

[aksh1552]

Ok, so now I am using a USB-6211 instead of the 6001. How should I proceed? The CI Angular Encoder function only helps me to find the angular position in clockwise direction, but what I want to measure is the actual position wrt to a reference, like when I turn the encoder in the counterclockwise direction I want the angle to get decremented, but in this function it gets incremented. 

[Kevin_Price]

There are several possible ways to change the sign convention for a quadrature encoder

1. Swap the physical wires for channels A and B

2. Leave the physical wiring, but swap the configuration so that the signal you used to define as B is now defined as A (and vice versa).

3. (Not 100% sure this is allowed).  Set your pulses per rev scaling to be a negative value.

However, upon a re-read, perhaps you didn't really set up your task for quadrature?  Or perhaps the encoder itself doesn't support it?

-Kevin P

[M.B.]

First, I would try to get it running in MAX to eliminate wrong wiring. Your encoder is on first sight a quadrature model with A B Z signals.

Click on your 6221 in MAX, create a new task with counter acquisition and then use the position measurement angular. Select a counter channel and the task window tells you now where to connect the A B Z wires. X4 decoding should be selected.

Start the task and if wiring is correct and the encoder is working then position counts up and down. Then you can input the appropriate scaling to get degrees and test Z reloading.

Or is it just a software function that does not work? Then please specifiy your problem better.